1. Field of the Invention
The present invention provides a height adjustment device adapted for a projection apparatus; and more particularly, it provides a height adjustment device for adjusting a slanting angle of a projected image in a projection apparatus by changing the height of the side of the projection apparatus.
2. Descriptions of the Related Art
With the rapid development of information propagating technologies, projection apparatuses have been used both in home A/V entertainment activities and in meeting presentations of business entities. Meanwhile, the evolvement of associated technologies has made projection apparatuses increasingly lightweight and miniaturized, which further contributes to the increasing popularity of these products.
In practice, a projection apparatus frequently needs to be adjusted in terms of the projection angle thereof according to the concrete surroundings of the user. For example, when a projection apparatus is used within a relatively restricted space or installed at a particular location, it would be difficult to position the projection apparatus as far back as possible to zoom in or to improve the quality of an image. In this case, the user may accomplish this goal by elevating the projection side of the projection apparatus to a certain elevation angle. Similarly, when a support or a platform on which the projection apparatus is installed is not leveled, the lateral tilting angle of the projection apparatus has to be adjusted in such a way that distortion will not occur in the projected image, thus ensuring the quality of the image projected.
FIG. 1 is a perspective view of a projection apparatus 1 of the prior art. The projection apparatus 1 has a height adjustment device 11 and a body 13 which further has a housing 10. The height adjustment device 11 is disposed below the front side of the body 13 and extends partially beyond the housing 10. For further illustration, a perspective view of the height adjustment device 11 is depicted in FIG. 2. The height adjustment device 11 has a clamp spring body 110, a clamp spring controlling element 111 and a screw 112. The clamp spring body 110 is formed with a hole 110a for the screw 112 to insert therethrough. The clamp spring controlling element 111 is connected with the clamp spring body 110 and engaged with a clamp spring (not shown) inside the clamp spring body 110 to fix the screw 112 within the hole 110a indirectly. Accordingly, the height adjustment device 11 adjusts the height in the following way: the clamp spring for clamping the screw 112 in the clamp spring body 110 is released by pressing the clamp spring controlling element 111, and then the projection apparatus 1 is lifted to manually adjust the extended length of the screw 112 to adjust the projection apparatus 1 to an appropriate height. Once the desired height is obtained, the clamp spring controlling element 111 is released and the clamp spring clamps and consequently fixes the screw 112 again.
However, in case the projection apparatus has a large weight, strenuous effort is needed to lift it up. Moreover, when the projection apparatus is lowered down, the potential shock or impact may be caused if the projection apparatus is not handled carefully or the clamp spring is not clamped to the screw securely, thus causing damage to the projection apparatus.
On the other hand, such height adjustment devices 11 are mostly adapted to change the height of the projected image by adjusting an elevation angle and the depression angle of the projection apparatus. However, the installation of a projection apparatus affects not just the height of an image projected. For example, when the projection apparatus is installed on an unleveled floor or a support, an image projected will be out of level, causing the slanting of the image in the left-right direction. Since the requirements on the slanting adjustment amount are lower than those on the height adjustment, only a fine tuning is required on the slanting angle. In this case, the height adjustment device 11 which delivers a substantial adjustment will not apply. For this reason, none of the projection apparatuses currently available are provided with an adjustment device for adjusting the slanting angle of an image.
In view of this, it is highly desirable in the art to provide a novel height adjustment device mainly adapted for the fine adjustment of the slanting angle in the left-right direction without requiring strenuous effort and causing potential damage to the projection apparatus.